How to correctly clean eggs for incubation?

It’s inevitable that some of your eggs will get dirty at some point and need cleaning. As mentioned in my earlier post about Why didn’t my eggs hatch?, eggshell has a thin outermost coating called the bloom or cuticle that helps keep out bacteria and dust. While the cuticle does provide a great barrier against contaminants, it does not prevent water to penetrate past its shell pores and pose a threat to microbial penetration. However, if the period of contact between egg and water is short, there will be little microbial penetration into the egg (Zeidler, 2002). Sometimes it will be necessary to wash your eggs in water if you can’t remove all of the dirt with dry cleaning alone.

There are 3 things that need mentioning here, so that all of your efforts won’t go in vain:

  1. ALWAYS clean and sterilize your incubator before and after each hatch. This includes brand-new incubator. There is absolutely no point in cleaning and sterilizing your eggs if you are then going to put them in an incubator that hasn’t also been sterilized.

  1. ALWAYS handle eggs with clean hands to avoid any cross-contamination. There is also no point in cleaning and sterilizing eggs if you handle them with dirty hands afterwards. Use an antibacterial hand sanitizer every time you open the lid and touch your eggs — especially if you’re turning the eggs by hand.
  1. ALWAYS sterilize everything that comes in contact with your eggs in any way — this includes your candler.

Part 1: Dry Cleaning Eggs

Step 1: inspect the eggs for any cracks or breaks before cleaning. Discard any cracked ones.

Step 2: Gently (I mean really gently) rub the egg with a sanding sponge or a loofah or a soft bristle toothbrush until the dirt comes away. Most dirt can be removed using a sanding sponge or a loofah. Try not to rub the areas that are already clean, this will keep as much of the bloom intact as possible.

It is a good idea to sanitize the sponge or loofah or brush between uses. This prevents bacteria being transferred from one egg to another.

Part 2: Washing and Sanitizing Eggs

Step 1: Decide whether you want to wash and sanitize your eggs. Wash only those eggs that you can’t remove all of the dirt with dry cleaning alone or are contaminated by large quantities of dirt or droppings.

If you plan on selling your eggs, you will need to comply with your state’s regulations regarding the proper cleaning and safety procedures for farm-fresh eggs. Some states require that you wash eggs, while others do not. So look up your state’s laws on egg sales.

Washington Egg Law:

https://agr.wa.gov/Marketing/SmallFarm/greenbook/docs/26.pdf

Minnesota Egg Law:

http://misadocuments.info/FactSheets/eggs_factsheet_092116_FINAL.pdf

Tennessee Egg Law:

https://publications.tnsosfiles.com/rules/0080/0080-05/0080-05-04.pdf

North Carolina Egg Law:

https://content.ces.ncsu.edu/explaining-the-north-carolina-egg-law-for-producers-with-small-flocks

Here is a comprehensive list of resources regarding egg laws by state throughout the U.S.

Step 2: Lightly spray the eggs with warm water, about 104°F (40°C), prior to washing will help loosen dirt on the shell (Hutchison et al., 2003).

Step 3: Fill two bowls with warm water that’s at least 20°F (11°C) warmer than the egg itself (IAMFES, 1976). A good water temperature is 90–120°F (32–49°C). If you use a colder water temperature, any dirt or bacteria on the eggshell can be sucked into the egg. To one of the bowls, add a little cleaning agent such as Brinsea® incubation disinfectant concentrate or a specific egg cleaning product, according to the manufacturers’ instructions. Cleaning agents generally raise water pH to 11 and the alkaline environment helps kill microbes, including Salmonella (Zeidler, 2002).

To the other bowl, add about ¼ to ½ teaspoon of bleach. I’ve seen many sources mention using bleach. If you don’t like the idea of using bleach, you can alternate it with distilled white vinegar, diluted in half with water.

Wear rubber gloves to protect your hands from becoming irritated by either the cleaning agent or bleach (or vinegar).

Step 4: Work gently, with one egg at a time, dip it into the water with the cleaning agent and use your fingers to clean off any hardened dirt. If necessary, use a soft bristle toothbrush. It is important that you do not soak the eggs in water with the cleaning agent. As mentioned above, if the period of contact between egg and water is short, there will be little microbial penetration into the egg (Zeidler, 2002). Therefore, it is important to limit the amount of time that the shell is wet. Soaking eggs in water for as little as one to three minutes can allow microbes to penetrate the shell (Zeidler, 2002).

After the initial wash, rinse the egg in clean warm water to clean off any cleaning agent (Zeidler, 2002), then dip the egg into the bleach (or vinegar) solution to sanitize. Set the egg on a piece of clean paper towel to dry by evaporation or with fan assistance or by wiping before packing and storing to prevent fungal and microbial growth.

Repeat the process with the remaining eggs.

If you have more than a few dozen eggs to wash, it will be necessary to refresh the bowls of water frequently.

Step 5: Once the eggs have been washed, sanitized and dried, you will need to store them correctly. Place eggs in a clean, sterile plastic egg carton or plastic storage box with their pointed ends facing downward. Date stamp the carton or use color coded stickers for easy identification.

Eggs should be stored in the main part of the refrigerator, at temperatures between 53–70°F (12–21°C) depending on the expected length of storage time before incubation, with a relative humidity level around 75–80% (see ‘Eggs too old when set’ of Why didn’t my eggs hatch?).

Eggs should be turned 1–2 times a day during storage, 45 degrees each time you turn, back and forth. If you’re storing them in a carton, which most people do, it means to tilt the carton, from 45 degrees one way to 45 degrees the other. This prevents the embryos from sticking to shells.

Further reading:

Why American Eggs Would Be Illegal In A British Supermarket, And Vice Versa

Why Most Americans Refrigerate Raw Shell Eggs and Europeans Often Don’t

Safe Handling of Eggs from Small and Backyard Flocks

 

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